World’s precious brown gold
According to the Food and Agriculture Organisation (FAO), there has been an increasing interest in anaerobic digestion of farm and household residues in many parts of the world.
Anaerobic digestion produces two main outputs: biogas and bio slurry, the digestate or digester effluent. While biogas is used to produce energy, the large potential of bio slurry has often been overlooked. A large part of both the scientific and grey literature focuses on the production of energy alone, but does not venture into the multiple uses and intricacies of bio slurry use. Technical organisations such as NGOs, extension services, local universities and small holders themselves are often not fully aware of the multiple benefits of bio slurry use, nor do they know of the risks associated with handling and applying it on their farm. This article attempts to synthesise findings of the growing peer-reviewed literature on bio slurry to provide a sound and scientific basis for its use. At the same time, it sets out to identify the various research gaps related to bio slurry.
India, being home to the largest cattle population in the world, has not realised the importance of bio slurry as yet. The government departments that should have focused on it are completely ignorant about this great resource which is RAMBAN for our problems of rural unemployment, soil degradation, food quality degradation and consequently human health. I have been researching since 2009 on how India can create jobs for rural youth and keep the villages neat and clean. My focus initially was on technologies to create more gas per kilogram of cattle dung. Having understood how our gobar gas schemes failed, I reached a dead-end. Thereafter I came across foreign research literature on bio slurry which has been equated with brown gold by FAO. The tipping point came when I contacted Gulab Bhai Patel, a social worker in Gujarat who has been working on gobar gas for more than 40 years now. He agrees about the importance of bio slurry over that of bio gas.
Bio gas has a problem of transportation from the production site. Solution to packing and transportation problem of bio gas came from Siemens social impact awardee Araya Asfaw’s project ‘biogas backpack’ which can carry one cubic metre of bio gas in three kilogram plastic bag.
Based on the above research, the importance of bio slurry and bio gas for India provided government departments can cater to the impetus in the form of legal, financial and research support for commercial exploitation of this great resource.
After green revolution and white revolution, bio slurry management can turn out to be the biggest of them all. The broad outline of my approach to wealth creation through bio-slurry is detailed below.
Objective of brown revolution
Creation of about one crore well paid jobs (Rs 10,000 per month at 2014 price level) in villages.
Making India self-reliant in its energy and organic fertiliser requirements.
Improving health of soil and people by producing bio slurry; the least understood nutrient rich organic fertiliser for organic food production.
Clean up the village side by transferring filth and disease causing cow dung to bio-digester which produces biogas as energy and pathogen free bio slurry as high quality plant nutrient, plant tonic and soil conditioner.
Save a part of about Rs 65,000 crore of fertiliser subsidy and about Rs 30,000 crore of kerosene annual subsidy (2014 figures).
Help save environment and earn carbon credit from ‘Kyoto Protocol’ as Methane is 20-22 times more hazardous than CO2
Saving on pesticides, insecticides, medicines and hospitalisation.
Helping people stay healthy and happy and improving soil health which has degraded due to use of chemical fertilisers.
Opportunities of developing/strengthening other sectors namely dairy, organic farming, organic food processing industries and other activities.
Need for policy intervention to support biogas and bio slurry industry
Organic materials create greatest filth and act as raw materials for the digesters making biogas and organic fertilisers. At the moment MNREGA is paying people for doing no work or useless work. Cleaning the village of organic waste could be the first good and intelligent shift. Anybody bringing organic waste to a registered bio digester can be paid on per kilo basis. A detailed methodology which is easy to operate and is tamper proof needs to be developed in this regard.
Why focus on bio slurry centric social enterprise model
Human and animal faecal matter and plant/agriculture/kitchen waste cause a number of diseases which are not well understood and managed, based on knowledge research and intelligent management. There is high correlation between unsafe human faecal disposal and the prevalence of gastro intestinal diseases. Recent research by WHO (2004) indicates prevalence of specific micro-organisms not only in human faeces but animal faecal matter too contain pathogens like E. Coli, Enterococcus, Rotavirus and Cryptosporidium). This suggests that management of human faeces alone is insufficient in breaking the ‘true’ faecal-oral-transmission route. Hence, there is a need to focus on animal waste management as well.
Livestock activities have significant impact on almost all aspects of environment including air, land, soil, water and biodiversity. The livestock business contributes among other things to water pollution, euthropication and the degeneration of grass lands. Livestock are estimated to be the main inland source of phosphorous and nitrogen contamination and one of the leading factors for nitrate pollution resulting in blue baby syndrome (Steinfeld et al, 2006). Animal waste is a significant source of microbiological contamination of drinking water sources as well as the cause for subsequent disease burden. One of the major causes of mortality and morbidity among children below two years of age is rotavirus infection. The major source of rotavirus is animal faeces and the consequent drinking water contamination. Despite the global recognition of animal waste as a major source of rotavirus, there have been limited environmental sanitation drives to reduce the prevalence and viral transmission in rural India.
Animal waste from about 485 million livestock population in India contributes to excess nutrients, pathogens, organic matter, solids, and odorous compounds to the environment (Ministry of Agriculture, 2006). Animal waste from farms, livestock/poultry, dairy production operations and stray animals severely affects water quality if not managed properly. Though crop-increasing value of animal faeces has been recognized, more than 50 per cent of the cattle dung produced in India is either burnt or remains unmanaged (Ministry of Agriculture 2006).
Traditionally, the cattle-dung, together with house sweeping, is collected in the open backyard, and removed from the homestead by carrying on head in a metal container/earthern ware.
The loose heap of dung and other agri and kitchen waste lie exposed to the sun, with the result that the raw organic matter dries up quickly and does not fully decompose. The water content, quite often full of chemicals and pathogens seeps down to contaminate ground water. Very often, a part of the dry dung is blown off by wind or washed away by rain. This can cause eutrophication (excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life) of surface waters, degradation of ground water quality, and threats to human health. Poor management of cow dung and inadequate hygiene practices are also responsible for contamination of the milk produced.
The most common way of disposal of cow-dung in rural areas is to convert it into dung cakes which are burnt as fuel in rural households. Burning the cow-dung not only adds to carbon emission which is a greenhouse gas leading to ozone layer depletion but also leads to eye and respiratory diseases mostly among women folks.
BBPA aims at turning the menace of organic waste into extremely useful organic fertilisers, bio gas which shall make our people and our soil (mother earth) healthy and create millions of jobs among rural youth who has today become either depressed, suicidal or an anti-social element.
People without even formal education who constitute a very large number can with little training and support can easily earn about Rs 10,000 per month by just collecting about 200 kg of cow dung , kitchen waste etc if he is equipped with right tools.
New Vision: Bio gas centric concepts and need for bio slurry
Government and NGOs worked since decades in popularising gobar gas plants but the results have been nothing to be proud of. The concept failed because focus has been on generation of biogas and its local use at production centre. Transporting it has been difficult, inconvenient and quite often impossible. So if after doing dirty work you do not get paid you do not do that work. Our new concept aims at creating a business model where people get decently paid for what they do. An ideal digester produces, on an average, just about 25 gms to 50 gms (depending on the season, feedstock, digester technology, use of additives etc) LPG equivalent biogas which does not make good business sense for someone to get engaged in this work to eke out his livelihood. The return on investment in terms of money and labour is not attractive. To make business attractive the whole thought process has to be reinvented by focusing on slurry management where bio gas is considered only a useful by product. One kg of gobar is mixed with 0.60 to one litre of water to make feedstock for a bio digester. It produces about 40 to 80 grams of biogas that contains about 24 to 48 grams of methane and balance Co2, H2s and moisture. If the methane is sold at Rs 30/kg then one gets only Rs 0.72 to Rs 1.44 per kilogram of raw dung. But almost 1,500 ml of slurry flows out on the ground and gets sun dried to make about 300-350 grams of organic fertiliser.
Catch, challenge and opportunity
Possibilities that need to be explored is in separation of liquid and semisolid parts from the slurry or sale of slurry as such. Both parts of the slurry are good organic fertilisers rich in nitrogen and other plant nutrients depending on the nature of the feedstock of the digester. They can be theoretically further enriched with locally available natural additives like single super phosphate from Rajasthan, fly ash from thermal power plants, bacterial inoculation, seaweed powder from Indian ocean seaweeds etc. Here comes the need for research, technology and knowledge of what is the kind of soil and what additional nutrients are needed for what crops. This precise understanding of the nutrient base of additives including knowledge of bacteria and vermin composting through earthworm can add tremendous value to the liquid and semisolid parts of slurry to make them great organic fertilisers for farmers to grow organic and healthy food. Easily an income of about Rs 6 to Rs 9.0 (wholesale price at production point) can be generated from approximately 1,000 to 1,500 ml of slurry coming out of digester per kilogram of cowdung/kitchen waste. Care must be taken that the bottom of the digester is leak proof so that pathogens and nutrients of the feed stock do not seep into ground to contaminate the ground water. So one kg of cowdung worth around Rs 0.50 can fetch minimum of Rs 6.75 worth of gas and fertilisers.
Further an innovative social enterprise can develop database of soil tests of nearby farmers and offer them attractive prices for the crops to be planted by them based on need, season and nutrient requirement of the crops and provide them organic fertilisers produced by the nearby digesters. Same crops can then be marketed as high quality organic produce including vegetables and fruits. This would benefit the soil, farmer, entrepreneurs and country at large and shall create well paid jobs for the rural youth who are facing severe unrest. We can create millions of rural jobs from the dung, human faeces, kitchen waste and plant waste. MNREGA money could be used to pay collectors of these waste materials that can be made available in ready to use form and supply to the digesters nearby. This shall clean up cities and villages of at least organic waste and make country free of diseases that they cause if left to rot.
The author is retired general manager, India Trade Promotion Organisation
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